Impact-machine



w. GEBHARD.

IMPACT MACHINE. APPLICATION FILED AUG.14. 1911.

Patented Jan. 13, 1920.

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IMPACT-MACHINE.

Application filed August 14,

To all whom it may concern:

it known that l, -i/Vrmrnn GERHARD, a

itizen of the United States, and a resident of the city of Chicago, county of Cook, and State of Illinois, have invented certain neu and useful Improvements in Impact-Machines, of which the following is a specifica tion.

My invention relates to improvements in impact machines and has for its object the provision of an improved mechanically operated impact or ham-mer machine, which is of simple construction and efficient in operation.

The invention consists in the combina tions and arrangements of parts hereinafter described and claimed.

The invention will be best understood by reference to the accompanying drawings forming a part. of this specification, and in which:

Figure 1 is a longitudinal section of an impact machine embodying my invention, and

Fig. 2, a transverse section of the same taken on line 22 of Fig. 1.

The preferred form of construction as illustrated in the drawings comprises a suitable casing or housing 3 having; a tool socket 4: at one end adapted to receive the shank of any usual or ordinary impact tool 5 as indicated. A hollow shaft 6 is rotatably mounted in the other end of easing 3 and arranged to be driven by means of a. gear 7 as shown. At its inner end shaft 6 carries an internal ratchet wheel 8 rotating in the upper end of the housing 3. Another hollow shaft 9 is rotatably mounted as indicated in shaft 6 and carries at its inner end a pawl arm 10 rotating within the ratchet wheel 8. Arm 10 carries at one end a pawl 11 normally engaging ratchet wheel 8 and provided with an inwardly extending finger or arm 12 engaged by spring 13, which normally holds pawl 11 in engagement with ratchet wheel 8. A. conical head 14 is provided at the inner end of a reciprocatory stein 15 loosely mounted in shaft 9 and normallyheld in retracted position by means of a leaf spring 16 as shown, the head 14 being arranged in contact with the inner end of arm 12. An adjusting screw 17 is arranged as shown to contact with the outer end of stem 15 to adjust the position of head 14, the arrangement being such that by adjusting head 14% the pawl 11 may be temporarily Specification of Letters, Patent.

Patented Jan-.13, 1920- 917. Serial No. 186,141.

withdrawn from operative engagement with ratchet wheel 8 as will be readily understood.

The other end of pawl arm 10 carries a crank pin 18 having a ball bearing connection 1 9 with one end of a thrust rod 20. The free end of the thrust rod 20 is provided with a cylinder 21 having a cylindrical impact or hammer head 22. slidably mounted therein and protruding from the end thereof. The hammer head 22 is provided with a central flange 23 having rubber or other resilient rings 2 1 imprisoned on each side thereof. The cylinder 21 is equipped with a bearing rim or flange- 25; arranged to both reciprocate and oscillate in and have frictional contact with the wallsof a cylindrical guide 26 to bring the hammer head 22: into impact contact with the shank of tool 5.

Bythis arrangement, it will be seen that, upon rotation of the shaft 6 the pawl 11 will engage with ratchet wheel 8 to impart an initial rotating motion to crank pin-18 and consequently to hammer head 22, until crank pin 18 reaches substantially its horizontal driving position or the position in which it imparts the maximum motion to the hammer head 22.

When the crank pin reaches this position, with a substantially uniform speed of rotation of shaft 6', its operative or driving speed commences to diminish following the law of a sine curve, but the inertia of the hammer head 22 and its associated parts, serves to continue this maximum speed and complete the stroke of said hammer head, automatically releasing the same from the ratchet wheel 8 and shaft 6. This action will take place through a wide variation in speeds of shaft 6, from a slow speed barely suflicient to impart suflicient inertia to the hammer to overcome the friction of the parts, to a comparatively high speed at which the blows of the hammer will take place with great rapidity and great force. This variation of the speed of shaft 6' serves as a means for varying not only the number of hammer blows per minute, but also the force with which the hammer strikes the work. When the hammer head 22 strikes the shank of the tool 5 the uppermost ring 24 is slightly compressed, thus permitting the crank pin 18 to pass the dead center, whereupon said ring reexpands, the pawl 11 automatically engages the ratchet wheel Q and the operation of the hammer head continuously repeated as long as the shaft 6 rotates. When it is desired to discontinue the operation of the hammer head, the screw 17 is adjusted until the pawl 11 is thrown out of operative relation with ratchet wheel 8, whereupon the operation of the hammer head 22 ceases. By this arrangement advantage is taken of the greatest operative speed imparted to the hammer head by the crank pin operating the same, it being well known that the reciprocatory motion imparted by a crank pin followsthe law of sine curve, that is, gradually increases in one direction to a maximum and then gradually returns to the Zero, where it reverses, gradually increasing to a maximum and then gradually returning to the zero, thus completing a cycle of movement. By means of the arrangement disclosed the operative speed imparted to the hammer head when the operative motion of the crank pin reaches its maximum is substantially con tinued, thus greatly increasing the eiiectiveness of the impact blow delivered by the hammer head.

in operation, as long as the internal ratchet revolves at a rotative speed equal to or greater than that of the o erating arm, the pawl thereon remains in engagemei'rt with said ratchet to effect a mechanical driving connection for said arm, but as soon as the rotative speed of the arm exceeds that of the ratchet, the pawl automatically releases, per mitting the hammer to continue its stroke under its own inertia or momentum to deliver the effective blow. 'ihis peculiar and important action or the hammer due to a combination of causes. As the crank pin passes the middle of its operative stroke, the longitudinal or driving component of its motion commences to decrease in proportion to its rotative motion, while the lateral component commences to increase. However, the hammer and its thrust arm have been given a longitudinal speed or thrust motion equal to the greatest peripheral speed or the crank pin as it passes the medial point oi its operative stroke. The inevitable result of this is that the inertia or momentum of the hammer and its thrust rod tends to carry the hammer longitudinally at the highest speed imparted thereto by the motion of the crank pin as it crosses said medial point. Obviously, as the tendency of the hammer and thrust rod is to maintain this highest longitudinal speed, and the tendency of the crank pin is to gradually decrease in longitudinal speed and increase in lateral speed, the hammer and connected parts must necessarily travel at a greater longitudinal speed than the corresponding parts of the ratchet. This being so, the rotative speed of the operating arm is momentarily increased over that of the ratchet, thus automatically releasing the operating arm from the driving connection with the ratchet, and this is true at all practical speeds, that is, all speeds above that speed which will impart an inertia or momentum to the hammer and thrust rod suiiicient to overcome the frictional resistance to their longitudinal motion. Inasmuch as the inertia or m0- mentum varies with the square of the velocity, it is apparent that the greater the speed of rotation the more pronounced will be this automatic release and continuation of the operative stroke of the impact hammer.

This peculiar action has highly important efiects upon the operation of the device. Obviously, it is practically impossible to deliver efl'ective longitudinal blows from a rotating crank pin, inasmuch as the longitudinal thrust of the crank pin decreasesand becomes nothing at the end of its operative motion, when the speed of the hammer should be at its greatest. For this reason, it has been hitherto impossible to provide a satisfactory impact hammer operating from a rotating crank pin or the like.

While the device has been illustrated in the drawings as in position to deliver a downward blow, which, of course, is the most effective blow deliverable, because the inertia of the hammer is then assisted by gravity, it is obvious that in so short a distance the influence of the force of gravity can be'but little, and that the device is equally applicable to deliver blows horizontally or upwardly. It is also obvious that the force of the blow delivered by the hammer is dependent directly upon the speed of the crank pin as it passes the medial point or its operative stroke, so that by varying the speed of rotation of the operating shaft the force of the efi'ective hammer blow may be also varied as desired.

/Vhile I have illustrated and described the preferred forms of construction for carrying my invention into efiect, these are capable of variation and modification without departing from the spirit of the invention. I therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

Having described my invention what i claim as new and desire to secure by Let ters Patent is:

l. A device of the class described comprising an impact member; and means for imparting initial operative motion to said member in the direction oi the impact and then releasing it to complete its operative stroke, substantially as described.

2. A device of the class described compr an impac member; and mechanical means for imparting initial operative ino- 'ticn to said member in the direction of the impact and then releasing it to complete its operative stroke, substantially as described.

3. A device 01 the class described com prising an impact member; means for imparting initial operative motion to said member and then releasing it to complete its operative stroke; and a yieldable connection between said member and said means, substantially as described.

A device of the class described comprising a reciprocatory impact member; and rotary means for imparting initial operative motion to said member in the direction of the impact and then releasing it to complete its operative stroke, substantially as described.

A device of the class described comprising a reciprocatory impact member; and rotary means for imparting initial operative motion to said member in the direction of the impact and then releasing it to complete its operative stroke and reengage after impact, substantially as described.

6. A device of the class described comprising a reciprocatory impact member; a thrust member connected therewith; a r0- tating element; and a connection between said thrust member and said rotating element arranged to release at maximum speed, substantially as described.

7. A device of the class described comprising a reciprocatory impact member; a thrust member connected therewith; a rotating element; and a connection between said thrust member and said rotating element arranged to release at maximum speed and reengage after impact, substantially as described.

8. A device of the class described comprising a guide; an impact member arranged to reciprocate and oscillate in said guide; a thrust member connected with said impact member; a rotating element; and a connection between said thrust member and said rotating element arranged to release at maximum speed, substantially as described.

9. A device of the class described comprising a guide; an impact member arranged to reciprocate and oscillate in said guide; a thrust member connected with said impact member; a. rotating element; and a connection between said thrust member and said rotating element arranged to release at maximum speed and reengage after impact, substantially as described.

10. A device of the class described comprising a casing; a tool socket at one end of said casing; a rotating internal ratchet wheel at the other end of said casing; a pawl arm mounted to rotate within said ratchet wheel; a spring held pawl on said pawl arm arranged to normally engage said ratchet wheel; a crank pin carried by said pawl arm; a thrust member operatively con nected with said crank pin at one end and mounted to slide and oscillate in said casing at the other end'in operative relation with said tool socket; a cylinder in the free end o1 said thrust member; an impact member yieldingly mounted in said cylinder and arranged to impact with a tool in said tool socket, substantially as described.

11. A device of the class described comprising a casing; a tool socket at one end of said casing; a rotating internal ratchet wheel at the other end of said casing; a pawl arm mounted to rotate within said ratchet wheel; a spring held pawl on said pawl arm arranged to normally engage said ratchet wheel; a crank pin carried by said pawl arm; a thrust memberoperatively connected with said crank pin at one end and mounted to slide and oscillate in said casing at the other end in operative relation with said tool socket; a cylinder in the free end of said thrust member; an impact member yieldingly mounted in said cylinder and arranged to impact with a tool in said tool socket; and means for temporarily throwing said pawl out of operative relation with said gear, substantially as described.

12. A device of the class described comprising an impact member; means for exerting frictional resistance to the operative stroke of said impact member; and means for imparting initial operative motion to said member in the direction of the impact and then releasing it to complete its operative stroke, substantially as described.

13. A device of the class described comprising a guide; an impact member arranged to reciprocate and oscillate in and have frictional contact with said guide; a thrust member connected with said impact member; a rotating element; and a connection between said thrust member and said rotating element arranged to release a maximum speed, substantially as described.

14. A device of the class described comprising a guide; an impact member arranged to reciprocate and oscillate in and have frictional contact with said guide; a thrust member connected with said impact memher; a rotating element; and a connection between said thrust member and said rotating element arranged to release at maximum speed and reengage after impact, substantially as described.

15. A device of the class described comprising a casing; a tool socket at one end of said casing; a rotating internal ratchet wheel at the other end of said casing; a pawl arm mounted to rotate within said rotating wheel; a spring-held pawl on said pawl arm arranged to normally engage said ratchet wheel; a crank pin carried by said pawl arm; a thrust member operatively connected with said crank pin at one end, and mounted to slide and oscillate in and have frictional contact with said casing at the other end in operative relation with said tool socket; a cylinder in the free end of said thrust member; and an impact member yieldingly mounted in said cylinder and arranged to impact with a tool in said tool socket, substantially as described.

16. A device of the class described comprising a casing; a tool socket at one end of said casing; a rotating internal ratchet wheel at the other end of said casing; a pawl arm mounted to rotate within said rotating wheel; a spring-held pawl on said pawl arm arranged to normally engage said ratchet wheel; a crank pin carried by said pawl arm; a thrust member operatively con nected with said crank pin at one end, and

mounted to slide and oscillate in and have frictional contact with said casing at the other end in operative relation with said tool socket; a cylinder in the free end of said thrust member; an impact member yieldingly mounted in said cylinder and arranged to impact with a tool in said tool socket; and means for temporarily throwing said pawl out of operative relation with said gear, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WERNER GERHARD. Witnesses:

CORNELIUS G. CRAINE, MAX CoNvIsHER. 

